Educating all children well is not only urgent but also feasible
within the next few decades

Over the past century, three approaches have been advocated to escape
the consequences of widespread poverty, rapid population growth, environmental
problems, and social injustices. The bigger pie approach says:
use technology to produce more and alleviate shortages. The fewer forks
approach says: make contraception and reproductive health care available
to eliminate unwanted fertility and slow population growth. The better
manners approach says: eliminate violence and corruption; improve
trade, the operation of markets, and government provision of public goods;
reduce the unwanted aftereffects of consumption, such as environmental
damage; and achieve greater social and political equity between young
and old, male and female, rich and poor (Cohen, 1995).

Providing all the world´s children with a high-quality primary and
secondary education, whether through formal schooling or by alternative
means, could, in principle, support all three of these approaches. Education
provides economic benefits (see "Why Quality Matters in Education"
on page 15 of this issue), builds strong societies and polities, and improves
health. It is also a widely accepted humanitarian obligation and an internationally
mandated human right.

The good news is that over the past century, access to education has
increased enormously, illiteracy has fallen dramatically, and a higher
proportion of people are completing primary, secondary, or tertiary education
than ever before. But huge problems remain. About 115 million children
of primary school age are not currently enrolled in school. Most are illiterate
and live in absolute poverty; the majority are female. Some 264 million
children of secondary school age are not currently enrolled. Large educational
disparities exist within and between countries. The quality of schooling
is often very low. Moreover, demographic projections suggest that developing
countries will have 80 million more children of primary and secondary
school age (typically 6—17 years old) by 2025 than now—an increase
of 6 percent to 1.35 billion.

In 1990, the global community pledged at the World Conference on Education
for All in Jomtien, Thailand, to achieve universal primary education (UPE)
and greatly reduce illiteracy by 2000. In 2000, when these goals had not
been met, it repeated the pledge, this time at the World Education Forum
in Dakar, Senegal, with a target date of 2015. The UN Millennium Development
Conference in 2000 also adopted UPE by 2015 as one of its goals, along
with the elimination of gender disparities in primary and secondary education
by 2015. But even the modest UPE goal now looks unlikely to be achieved
by 2015 at the current rate of progress. An estimated 335 million school-age
children will be missing primary or secondary school in 2015; of these,
an estimated 118 million will be absent from primary school. About one
in five of these children will never enroll in or attend school.

Given this series of missed targets, what is feasible? Estimates are
that UPE can be achieved by 2015 if the global community invests another
$6 billion to $35 billion per year, on top of the approximately $82 billion
developing countries already spend each year on primary education. This
article argues that this sum is not only affordable but essential. It
also argues that the UPE goal is not ambitious enough: the world should
aim for, and can achieve, high-quality, universal secondary education,
possibly by 2015 but certainly by the middle of the 21st century. The
price tag for achieving this goal might be an additional $27 billion to
$34 billion per year starting now, on top of the approximately $93 billion
developing countries already spend each year on secondary education. However,
the obstacles are not just financial. Leaders need to devise and implement
policies that will make educating children unquestionably worthwhile,
in the eyes of parents and everyone else.

Education today

How is the global community doing in enrolling more children in school?
Are educational data reliable and useful for international comparisons?

The good. Remarkable progress has been made in formal schooling
over the past century, especially as measured by the primary gross enrollment
ratio (GER)—the ratio of the number of children enrolled in primary
education, regardless of age, to the population of the age group that
corresponds to the nationally defined ages for primary schooling.

In 1900, estimated primary GERs were below 40 percent in all
regions except northwestern Europe, North America, and Anglophone regions
of the Pacific, where the ratio was 72 percent (Williams, 1997). But
by 2000, the estimated global primary net enrollment ratio (NER)—the
ratio of the number of children in the official primary school age group
enrolled in primary education to the population of the primary school
age group—had reached 85 percent globally. The NER is a stricter
standard than the GER, so the achievement is all the more remarkable.

In developing countries, literacy tripled in the 20th century, from
25 percent to 75 percent, and the average years of schooling more than
doubled between 1960 and 1990, increasing from 2.1 to 4.4 years (Bloom
and Cohen, 2002). That figure has risen further since 1990.

The number of students enrolled in secondary school increased tenfold
in the past 50 years, roughly from 50 million to 500 million.

As for data quality, developing countries have begun to participate in
international measurements of educational status in greater numbers. Even
so, more statistical measures of schooling have been defined (for example,
net and gross enrollment ratios, attendance rates, completion rates, average
years of attainment, and school life expectancy) than are well supported
by reliable, internationally comparable, and comprehensive data. The UNESCO
Institute for Statistics, Montreal, maintains the highest-quality data
(for example, UNESCO, 2000, 2004).

The bad. While progress is being made, colossal shortfalls
remain.

Roughly 380 million children are not enrolled in school (28 percent
of the age group, typically 6).

More than one-fourth of these children are absent from primary school
(with the rest missing secondary school).

Of school-age children who enter primary school in developing countries,
more than one in four drops out before attaining literacy (World Bank,
2002).

Moreover, enrollment does not necessarily mean attendance, attendance
does not necessarily mean receiving an education, and receiving an education
does not necessarily mean receiving a good education. Thus the high enrollment
ratios may give the mistaken impression that a high proportion of school-age
children is being well educated. Some 75 percent of the world´s
children live in countries where the quality of education lags behind—most
often far behind—the average of industrial countries, as measured
by standardized test scores. That standard may not be universally appropriate.
However, it is uncontested that educational quality is too often poor.

On the data front, indicators of educational quality are scarce. Though
participation in international and regional assessments of educational
quality has increased, countries most in need of improvements are least
likely to participate.

The ugly. Gross disparities in education separate regions,
income groups, and genders.

The populations farthest from achieving UPE are typically the world´s
poorest. In sub-Saharan Africa, the primary NER is only 63 percent—far
below the 96 percent in Latin America and the Caribbean (see Table 1).

Girls´ education falls short of boys´ education in much
of the world. While enrollment rates sometimes do not differ greatly,
many more boys than girls complete schooling, especially at the primary
level.

A systematic global analysis remains to be done, region by region, of
how much gender, urban or rural residence, and high or low income contribute
to differences in children´s educational opportunities and achievements,
but we know they interact. In India in 1992, for example, the
enrollment rate of boys ages 6 exceeded that of girls by 2.5 percentage
points among children of the richest households; the difference in favor
of boys was 24 percentage points among children from poor households (Filmer,
2000). Girls are more disadvantaged relative to boys in poor homes. The
boys from rich households had enrollment rates 34 percentage points higher
than those of boys from poor households; the gap in favor of rich girls
compared with poor girls was 55.4 percentage points. Wealth gaps in enrollment
greatly exceeded gender gaps in enrollment.

Table
1.
Joining school
Net primary enrollment ratios have advanced in most of the developing
world but remain low in sub-Saharan Africa.

World

Countries in transition
Developed countries
Developing countries

Arab states
Central and Eastern Europe
Central Asia
East Asia and the Pacific
Latin America and the Caribbean
North America and Western Europe
South and West Asia
Sub-Saharan Africa

199082

89
96
80

75
90
85
96
86
97
73
55

199884

85
97
82

78
87
89
96
94
96
79
56

200285

89
96
83

83
89
90
92
96
95
83
63

Source:
UNESCO Institute for Statistics.

Note: Net primary enrollment ratio (in percent) is
defined as the ratio of the number of children in the official primary
school age group enrolled in primary education to the population
of the primary school age group.

Spending on primary education varies widely among developing countries,
ranging from $46 per student per year in South Asia and $68 in sub-Saharan
Africa to $878 in Eastern Europe and Central Asia (see Table 2). Spending
per student in secondary education shows a similar disparity, ranging
from $117 per student per year in South Asia and $257 in sub-Saharan Africa
to $577 in Latin America and the Caribbean.

More money for education usually results in better education, but exceptions
to this pattern are informative. A 2001 study of Latin American primary
education showed that Cuba led in test scores, completion rates, and literacy
levels. The lowest fourth of Cuban students performed above the regional
average in third and fourth grade mathematics and language achievement,
although most nations of the hemisphere spent more public money per student
than the less than $1,000 spent in Cuba (Marquis, 2001). This example
suggests that policymakers, who are acutely aware of the competing demands
on resources, might do well to investigate how some countries have achieved
so much with only modest funds.

Financial obstacles

What would it cost to achieve both universal primary and secondary education?
At best, crude estimates are available, but the combined total falls between
$34 billion and $69 billion per year (see Box 1). This is a huge amount
of money, but certainly not beyond the ability of the world to fund. If
investments in education promote economic growth in the poorer countries
as anticipated, the share of income devoted to primary and secondary education
should decline.

How much could countries afford to spend? The World Bank estimates that
the low-income countries, with a population of about 2.4 billion, had
a combined gross national income (GNI) of almost $1 trillion in 2000 (with
an average annual per capita income of $410). The incremental cost of
$34 billion—$69 billion per year would be 3 percent of their GNI,
assuming they shouldered the entire incremental burden without any external
help. The low- and middle-income countries, with a population of nearly
5.1 billion, had a combined GNI of nearly $6 trillion (with an average
annual per capita income of $1,160). The incremental cost for them would
be about 0.6-.2 percent of their GNI.

South Asia
Sub-Saharan Africa
East Asia and the Pacific
Latin America and the Caribbean
Middle East and North Africa
Eastern Europe and Central AsiaDeveloping World

Public
spending
per student
(dollars)

46
68
103
440
519
878
1512

Total
public
spending
(million
dollars)

6,900
6,100
21,200
28,200
14,200
5,200
81,800

Percentage
of
population
with public
spending data1

98
98
96
90
60
22
882

Source:
Glewwe and Zhao, 2005.1Public spending figures are more reliable
in regions where public spending data are available for a higher
fraction of the population.2Averages weighted by number of pupils.

Of course, if the richer countries shared the cost, the burden on the
poorer countries would be less. The GNI of the high-income countries was
$25.5 trillion—out of the entire world´s $31.5 trillion—so
an extra $70 billion per year would be less than 0.3 percent of their
income. Official development assistance (ODA) in 2003 was $69 billion,
the highest ever in nominal and real terms. However, this amount was only
0.25 percent of donors´ combined GNI. Moreover, it was well short
of the average of 0.33 percent of ODA/GNI achieved in 1980 and of the
United Nations´ ODA target of 0.7 percent. Thus, the incremental
cost of $34 billion—$69 billion per year could consume up to the
entire pie of recent ODA.

Box 1Putting a price tag on education for all

Assuming education will be delivered largely through schools,
educating all children will require additional money for schools,
teachers, teacher training, materials and equipment, administration,
assessments, randomized evaluations, and overcoming economic disincentives
to families.

To achieve universal primary education (UPE) by 2015,
the World Bank, UNICEF, and UNESCO have estimated the annual costs
at between $9.1 billion and $35 billion per year, although a recent
detailed Bank study suggests that the price tag might be as low
as $6.5 billion per year. These investigations focus on the cost
of increasing the number of places for students in schools. However,
the number of places available is often not the limiting factor.
Future cost estimates should reckon the cost of providing other
improvements necessary to encourage students to attend school—such
as meals, tuition subsidies to families, improvements in the quality
and reliability of teaching, and reductions in rates of repetition
and non-completion. In other words, the true cost of UPE will
include the cost of implementing policies to boost the demand
for primary education, and current estimates overlook this cost.

To achieve universal secondary education, the cost will
be greater than that for UPE because more children in this age
bracket are not in school and secondary education is more expensive
per pupil. If a gradual approach is taken between now and 2015,
the annual additional cost would likely be between $27 billion
and $34 billion. If an instantaneous expansion of secondary education
is sought, a recent pioneering study suggests that the cost would
be $28 billion to $62 billion annually, at least under current
policies (Binder, 2005). But this cost could fall to $47 billion
if policymakers adopted the practices of countries most successful
in making schooling available to students, getting students to
attend school, and helping them learn while they are in school.
The best (albeit unlikely) scenario, including a sharp drop in
repetition rates, would reduce the extra annual cost to $28 billion.
The biggest expansion of secondary education will be needed in
the poorest countries, where the average per-student yearly cost
is $126, compared with $244 in low-income countries and $884 in
upper-middle-income ones.

As public funds are limited, it is natural to ask: Is education the best
use of the marginal dollar of government expenditure in a developing country?
Should that dollar be spent on education rather than health, physical
infrastructure, or applied research? Unfortunately, we know no convincing
answers to these questions, even if the "best use" is interpreted
narrowly as economically most efficient. Credible models to evaluate the
trade-offs for human well-being between education and other sectors of
public investment appear to be lacking. The same fundamental lack of knowledge
applies to the trade-offs between primary and secondary or higher education.
However, the difficulty of achieving universal education is about a lot
more than money.

Nonfinancial obstacles

What are the nonfinancial obstacles to achieving universal primary and
secondary education? Studies show that they are economic, competitive,
informational, political, cultural, and historical.

Economic disincentives. Millions of children have access
to schooling but do not attend. One explanation is that their families
value more the time these children spend in other activities, such as
performing work for income or handling chores so other household members
are free to work in market activities. A troubled household economic situation
is more often a deterrent to enrollment than lack of access to a school.
For example, a World Bank study in Ghana found that almost half of parents,
when asked why their children were not in school, answered "school
is too expensive" or "child needed to work at home." Another
22 percent believed that education was of too little value. Lower market
wages for women can make investing in schooling for boys before schooling
for girls a rational economic decision for a family.

Competing demands. Education competes for scarce national
resources with many worthy projects, such as building roads, providing
medical care, and strengthening national defense. Limited resources can
hamper educational expansion in many ways. Organized interest groups may
divert funding from education to their own causes. When social crises,
such as crime, unemployment, or civil war, demand the time and resources
of the government, citizens may support channeling resources to remedy
these crises rather than to education. A limited capacity to oversee the
implementation of education programs and the limited status of education
ministries within many governments may also pose problems. Competing demands
from business and other employers may limit the supply of people qualified
to be primary and secondary teachers.

Lack of information. Reliable, internationally comparable,
useful data on many aspects of primary and secondary education are lacking.
For example, the mechanisms that keep children out of school are poorly
understood in quantitative (as opposed to qualitative) detail. Most routine
data focus on measures of "butts-in-seats" (in the expressive
language of World Bank economist Lant Pritchett), such as enrollment,
attendance, and completion. Political incentives sometimes work against
accurate reporting. In Uganda, enrollment was historically underreported
because schools were required to remit private tuition receipts to the
government in proportion to the number of students they reported. When
schools became publicly funded on the basis of enrolled pupils, the incentive
for schools to report higher numbers resulted in a leap in official enrollments.
Governments may also be reluctant to publish potentially unflattering
data on their school systems for fear of political consequences.

Political obstacles. Politics may stymie educational expansion
for other reasons. The long time horizon over which educational returns
accrue greatly exceeds the short time horizon of political incumbents.
When politicians devote funds to education, the funding sometimes flows
to political supporters rather than to programs and regions where it is
most needed.

Cultural barriers. Discrimination may inhibit educational
participation, particularly for girls and for linguistic, religious, and
ethnic minorities. Verbal and physical abuse; a lack of functional, secure
toilets for girls; and long distances between home and school can deter
parents from sending daughters to school. Where girls are expected to
care for family members and to perform household chores, education may
be seen as unnecessary. Girls´ education may also be seen as a low
priority if they leave their parents´ household upon marriage.

Historical context. Past national models and motivations
for education have been diverse. Solutions that ignore the history of
education in a particular country are likely to be less effective than
solutions tuned to context. Attempts to decentralize education in Latin
American countries in the 1980s ignored the social and political purpose
of using schooling to end severe socioeconomic segregation. Decentralization
led to a growth of private schools and renewed fragmentation along socioeconomic
lines, which exacerbated the social divide that school centralization
was intended to correct.

Judging quality and effectiveness

Inadequate information about the quality of education complicates matters.
Without it, quality is unlikely to improve, which, in turn, undercuts
efforts to mobilize the money and motivation to achieve high-quality primary
and secondary education. International assessments, which are largely
based on OECD models, can be very useful but may not be optimal for all
countries. For some countries, national assessments focused on country-specific
curricula or regional approaches provide more relevant information—given
that every assessment implies stated or unstated goals of education, and
these goals are highly diverse.

Using educational assessments. When properly carried out,
assessments allow individuals and communities to track the quality of
schools and systems. If policymakers make information on educational quality
in specific schools and curricula available to the public, then students
and parents may be better able to choose among educational options and
demand education of higher quality. The Southern African Consortium for
Monitoring Education Quality is a regional learning assessment study introduced
by UNESCO and now governed by the 14 southern African participating governments.
It aims to identify within-country disparities in education as a guide
to where interventions might be needed.

Developing reliable and useful assessments requires institutional capacity,
technical expertise, and money—all likely to be scarce in developing
countries. Moreover, when assessments are tied to funding decisions, teachers,
administrators, and state officials may oppose creating or releasing such
data. Encouraging developing countries to participate in international
assessments as "associates" (so that results need not be released
internationally) will promote the generation of much-needed data, give
access to expertise, and build local capacity to develop, administer,
and analyze tests, while avoiding the political consequences of possible
poor performance by participating countries.

Using randomized experiments. Many traditional practices in education
have never been evaluated by scientific experimentation to measure quantitatively
what they contribute to educational outcomes. Would students learn arithmetic
or history less effectively if they were not required to be in their seats
by the time the school bell rang? Few innovations in education have been
rigorously compared with traditional practices. Does a student who learns
touch typing from a computer learn any better, or at a significantly lower
cost, than a student who learns from a traditional teacher or by self-instruction
from a printed book?

A reliable means of getting answers to questions like these—namely,
randomized controlled experimentation, the gold standard for evaluating
treatments in medicine—is now finding use in education. Such experiments
make possible valid comparisons among pedagogical techniques and systems
of management because randomization establishes equivalent participant
and nonparticipant groups for comparison. These experiments can, therefore,
produce the most credible assessment of programs, including their cost-effectiveness
(see Box 2).

Randomized evaluations are most powerful when applied narrowly to test
isolated variations. Without a theory of why the program has the effect
it has, generalizing from one well-executed randomized evaluation may
be unwarranted. Similar questions about wider application arise no matter
what evaluation technique is used. Given positive results from any evaluation
of a key innovation, one useful step would be to encourage adapted replications
of randomized evaluations in several different settings.

Unfortunately, randomized evaluations remain underutilized guides. Many
people assume the reason for this is that these experiments are expensive
and time consuming, and require technical sophistication to plan, implement,
and analyze properly. But, in fact, they are no more expensive or time
consuming than other rigorous data collection. More likely, they are underused
because it can be politically difficult to deliver a program to only a
sample of students or schools while withholding it from a comparison group.
However, when budgetary constraints make it difficult or impossible to
reach all members of a population in a given year, randomly selecting
which groups receive the program in year one, year two, and so on, may
be the fairest way to implement the program and simultaneously permit
measurements of its impact. Using randomized phase-ins addresses the trade-off
between evaluating and scaling up programs.

Box 2Can deworming boost attendance?

For policymakers trying to figure out which educational programs
are cost effective and which ones are not, there is growing evidence
that randomized evaluations—long used in the medical field—provide
valuable insights. Indeed, a recent study by Harvard University´s
Michael Kremer reports that randomized evaluations of school-based
health programs in Kenya for deworming and India for anemia show
that simple and inexpensive health treatments can dramatically
boost attendance (Kremer, 2004).

In western Kenya, the researchers evaluated a twice-yearly primary
school deworming program that was phased in over several years.
The researchers randomized the order in which schools were phased
in to ensure statistically reliable comparisons between the schools
with and those without the deworming program. They found that
child health and school participation improved not only for treated
students but also for untreated students at treatment schools
and untreated students at nearby nontreatment schools due to reduced
disease transmission. The direct effect of the deworming program,
including within-school health spillovers, resulted in a 7.5 percent
average gain in primary school participation in treatment schools
and a reduction in absenteeism of at least 25 percent. When cross-school
externalities were included, they found that deworming also resulted
in a 2 percent average gain for pupils in nontreatment schools.
They estimated that the cost per extra year of school participation
was only $3.50, making deworming an extremely cost-effective way
of boosting attendance.

Defining the goals. Assessments and evaluations presume goals
for what education should accomplish. Who should decide educational goals?
What relative weight should be given to the voices of parents, children,
politicians, clerics, educational experts, leaders of business, labor
and the community, and others? How should the weight attached to the views
of different claimants for influence be decided? These questions need
more public discussion and policy attention than they currently receive,
and thus should be encouraged by governments and international organizations.

Proposed educational goals include reading, writing, and arithmetic;
readiness for the local or global labor market; health knowledge and healthy
behavior; the creation (or sustaining) of a more cohesive society; the
capacity to adapt to ceaseless change and to learn under conditions of
freedom; assisting youths to fulfill their physical, emotional, social,
spiritual, and intellectual potential; providing the competencies children
need for their lives and livelihoods; enabling students to interact in
socially heterogeneous groups, act autonomously, and use tools; learning
to know, to do, to live with others, and to be (Delors, 1998); addressing
the needs of the world´s poorest children and youth, those the global
economy has left behind; promoting tolerance rather than hatred; and opening
people´s minds rather than controlling them.

Five changes needed

Universal, high-quality primary and secondary education is achievable
by the middle of the 21st century. But at the current rate of progress,
by 2015 roughly 118 million children of primary school age will still
not be enrolled in primary education and 217 million of secondary school
age will still not get a secondary education (16 percent and 30 percent
of the relevant populations, respectively), according to our estimates.
What is needed now? No single magic bullet will bring high-quality primary
and secondary education to all the world´s children. Rather, at least
five complementary, interacting changes are needed:

open discussions, nationally, regionally, and internationally, on
what people want primary and secondary education to achieve—that
is, the goals of education;

a commitment to improving the effectiveness and economic efficiency
of education in achieving those goals, whether through formal schooling
or other means; this improvement should be driven by reliable data on
what children learn; careful experiments with alternative pedagogical
techniques and technologies; and comparative studies of the countries
that perform best, region by region, within any given level of funding
and material resources;

a commitment to extending a full cycle of high-quality secondary
education to all children;

international recognition of the diverse character of educational
systems in different countries, and adaptation of aid policies and educational
assessment requirements to local contexts; and

more money and higher priority for education—especially an
increase in the absolute and relative amount of funding from rich countries
for education in poor countries.

The goal of providing high-quality primary and secondary education to
all the world´s children is as inspiring and formidable a challenge
as any extraterrestrial adventure—and far more likely to enrich
and improve life on earth, even in ways that may be difficult to anticipate
today.

References:

Binder, Melissa, 2005, "The Cost of Providing Universal
Secondary Education in Developing Countries," American Academy
of Arts and Sciences Working Paper (Cambridge, Massachusetts:
American Academy of Arts and Sciences).

Cohen, Joel E., 1995, How Many People Can the Earth Support?
(New York: W. W. Norton).

Delors, Jacques, and others, 1998, "Learning: The Treasure
Within: Report to UNESCO of the International Commission on Education
for the Twenty-first Century," 2nd Pocket edition (Paris:
UNESCO Publishing).

Filmer, D., 2000, "The Structure of Social Disparities
in Education: Gender and Wealth," prepared as background
paper for Engendering Development Through Gender Equality
in Rights, Resources, and Voice (Washington: World Bank).

Glewwe, Paul, and Meng Zhao, 2005, "Attaining Universal
Primary Completion by 2015: How Much Will It Cost?" American
Academy of Arts and Sciences Working Paper (Cambridge, Massachusetts:
American Academy of Arts and Sciences).

Kremer, Michael, 2004, "The Role of Randomized Evaluations
in Making Progress Towards Universal Basic and Secondary Education,"
American Academy of Arts and Sciences Working Paper (Cambridge,
Massachusetts: American Academy of Arts and Sciences).

United Nations Educational, Scientific, and Cultural Organization,
2000, "Education for All 2000 Assessment: Statistical Document,"
prepared for the International Consultative Forum on Education
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Available at http://unesdoc.unesco.org/images/0012/001204/
120472e.pdf.

Williams, James H., 1997, "The Diffusion of the Modern
School," in William K. Cummings and Noel F. McGinn, International
Handbook of Education and Development: Preparing Schools, Students
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Elsevier Science).

World Bank, 2002, Education and HIV/AIDS: A Window
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Joel E. Cohen
is Abby Rockefeller Mauzé Professor of Populations at the Rockefeller
University and Professor of Populations at Columbia University in
New York City. David E. Bloom is Clarence James Gamble Professor
of Economics and Demography at the Harvard School of Public Health,
Boston. The authors codirect the project on Universal Basic and Secondary
Education (http://www.amacad.org/projects/ ubase.aspx) of the American
Academy of Arts and Sciences with major funding from the Hewlett Foundation.
This article draws heavily on work done as part of that project by
Aaron Benavot, Eric Bettinger, Melissa Binder, David Bloom, Henry
Braun, Claudia Buchmann, David Canning, Mohammed Charfi, Kai-ming
Cheng, Joel Cohen, Javier Corrales, Paul Glewwe, Emily Hannum, Anil
Kanjee, Michael Kremer, Ruth Levine, Martin Malin, Stephen Provasnik,
Mohammed Redissi, Julia Resnik, Larry Rosenberg, and Laura Salganik.
Albert Motivans and colleagues at the UNESCO Institute for Statistics
provided helpful input.